Esercizi Lettura MySQL C++

Codegrind Team•Jul 12 2024

Ecco degli esercizi semplici con soluzione per praticare la lettura di dati in MySQL utilizzando C++ sia in modo sequenziale che OOP.

Esercizio 1: Lettura di un singolo record usando MySQL Connector/C++ (metodo sequenziale)

Stabilire una connessione a MySQL e leggere un singolo record.

#include <mysql_driver.h>
#include <mysql_connection.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
#include <cppconn/resultset.h>
#include <iostream>

int main() {
    sql::mysql::MySQL_Driver* driver = sql::mysql::get_mysql_driver_instance();
    std::unique_ptr<sql::Connection> con(driver->connect("tcp://127.0.0.1:3306", "root", "password"));
    con->setSchema("test_db");

    std::unique_ptr<sql::PreparedStatement> pstmt(con->prepareStatement("SELECT * FROM test_table WHERE name = ?"));
    pstmt->setString(1, "John Doe");
    std::unique_ptr<sql::ResultSet> res(pstmt->executeQuery());

    if (res->next()) {
        std::cout << "ID: " << res->getInt("id") << ", Name: " << res->getString("name") << ", Age: " << res->getInt("age") << std::endl;
    } else {
        std::cout << "Record non trovato" << std::endl;
    }

    return 0;
}

Esercizio 2: Lettura di più record usando MySQL Connector/C++ (metodo sequenziale)

Stabilire una connessione a MySQL e leggere più record.

#include <mysql_driver.h>
#include <mysql_connection.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
#include <cppconn/resultset.h>
#include <iostream>

int main() {
    sql::mysql::MySQL_Driver* driver = sql::mysql::get_mysql_driver_instance();
    std::unique_ptr<sql::Connection> con(driver->connect("tcp://127.0.0.1:3306", "root", "password"));
    con->setSchema("test_db");

    std::unique_ptr<sql::PreparedStatement> pstmt(con->prepareStatement("SELECT * FROM test_table WHERE age > ?"));
    pstmt->setInt(1, 20);
    std::unique_ptr<sql::ResultSet> res(pstmt->executeQuery());

    while (res->next()) {
        std::cout << "ID: " << res->getInt("id") << ", Name: " << res->getString("name") << ", Age: " << res->getInt("age") << std::endl;
    }

    return 0;
}

Esercizio 3: Lettura di un singolo record usando MySQL Connector/C++ (OOP)

Creare una classe per gestire la connessione a MySQL e leggere un singolo record.

#include <mysql_driver.h>
#include <mysql_connection.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
#include <cppconn/resultset.h>
#include <iostream>

class MySQLClient {
private:
    sql::mysql::MySQL_Driver* driver;
    std::unique_ptr<sql::Connection> con;
public:
    MySQLClient(const std::string& host, const std::string& user, const std::string& pass, const std::string& db) {
        driver = sql::mysql::get_mysql_driver_instance();
        con.reset(driver->connect(host, user, pass));
        con->setSchema(db);
    }

    void leggiRecordSingolo(const std::string& query, const std::string& name) {
        std::unique_ptr<sql::PreparedStatement> pstmt(con->prepareStatement(query));
        pstmt->setString(1, name);
        std::unique_ptr<sql::ResultSet> res(pstmt->executeQuery());

        if (res->next()) {
            std::cout << "ID: " << res->getInt("id") << ", Name: " << res->getString("name") << ", Age: " << res->getInt("age") << std::endl;
        } else {
            std::cout << "Record non trovato" << std::endl;
        }
    }
};

int main() {
    MySQLClient client("tcp://127.0.0.1:3306", "root", "password", "test_db");
    client.leggiRecordSingolo("SELECT * FROM test_table WHERE name = ?", "John Doe");
    return 0;
}

Esercizio 4: Lettura di più record usando MySQL Connector/C++ (OOP)

Creare una classe per gestire la connessione a MySQL e leggere più record.

#include <mysql_driver.h>
#include <mysql_connection.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
#include <cppconn/resultset.h>
#include <iostream>

class MySQLClient {
private:
    sql::mysql::MySQL_Driver* driver;
    std::unique_ptr<sql::Connection> con;
public:
    MySQLClient(const std::string& host, const std::string& user, const std::string& pass, const std::string& db) {
        driver = sql::mysql::get_mysql_driver_instance();
        con.reset(driver->connect(host, user, pass));
        con->setSchema(db);
    }

    void leggiRecordMultipli(const std::string& query, int age) {
        std::unique_ptr<sql::PreparedStatement> pstmt(con->prepareStatement(query));
        pstmt->setInt(1, age);
        std::unique_ptr<sql::ResultSet> res(pstmt->executeQuery());

        while (res->next()) {
            std::cout << "ID: " << res->getInt("id") << ", Name: " << res->getString("name") << ", Age: " << res->getInt("age") << std::endl;
        }
    }
};

int main() {
    MySQLClient client("tcp://127.0.0.1:3306", "root", "password", "test_db");
    client.leggiRecordMultipli("SELECT * FROM test_table WHERE age > ?", 20);
    return 0;
}

Esercizio 5: Lettura di un singolo record usando MySQL C API (metodo sequenziale)

Stabilire una connessione a MySQL e leggere un singolo record usando MySQL C API.

#include <mysql/mysql.h>
#include <iostream>

int main() {
    MYSQL* conn = mysql_init(nullptr);
    if (conn == nullptr) {
        std::cerr << "mysql_init() failed\n";
        return EXIT_FAILURE;
    }

    if (mysql_real_connect(conn, "localhost", "root", "password", "test_db", 0, nullptr, 0) == nullptr) {
        std::cerr << "mysql_real_connect() failed\n";
        mysql_close(conn);
        return EXIT_FAILURE;
    }

    const char* query = "SELECT * FROM test_table WHERE name = 'John Doe'";
    if (mysql_query(conn, query)) {
        std::cerr << "SELECT failed. Error: " << mysql_error(conn) << std::endl;
        mysql_close(conn);
        return EXIT_FAILURE;
    }

    MYSQL_RES* res = mysql_store_result(conn);
    if (res == nullptr) {
        std::cerr << "mysql_store_result() failed. Error: " << mysql_error(conn) << std::endl;
        mysql_close(conn);
        return EXIT_FAILURE;
    }

    MYSQL_ROW row;
    if ((row = mysql_fetch_row(res))) {
        std::cout << "ID: " << row[0] << ", Name: " << row[1] << ", Age: " << row[2] << std::endl;
    } else {
        std::cout << "Record non trovato" << std::endl;
    }

    mysql_free_result(res);
    mysql_close(conn);
    return EXIT_SUCCESS;
}

Esercizio 6: Lettura di più record usando MySQL C API (OOP)

details class=“mb-10”>

Creare una classe per gestire la connessione a MySQL e leggere più record usando MySQL C API.

#include <mysql/mysql.h>
#include <iostream>
#include <stdexcept>

class MySQLClient {
private:
    MYSQL* conn;
public:
    MySQLClient(const std::string& host, const std::string& user, const std::string& pass, const std::string& db) {
        conn = mysql_init(nullptr);
        if (conn == nullptr) {
            throw std::runtime_error("mysql_init() failed");
        }
        if (mysql_real_connect(conn, host.c_str(), user.c_str(), pass.c_str(), db.c_str(), 0, nullptr, 0) == nullptr) {
            mysql_close(conn);
            throw std::runtime_error("mysql_real_connect() failed");
        }
    }

    ~MySQLClient() {
        mysql_close(conn);
    }

    void leggiRecordMultipli(const std::string& query, int age) {
        std::string full_query = query + std::to_string(age);
        if (mysql_query(conn, full_query.c_str())) {
            throw std::runtime_error("SELECT failed: " + std::string(mysql_error(conn)));
        }

        MYSQL_RES* res = mysql_store_result(conn);
        if (res == nullptr) {
            throw std::runtime_error("mysql_store_result() failed: " + std::string(mysql_error(conn)));
        }

        MYSQL_ROW row;
        while ((row = mysql_fetch_row(res))) {
            std::cout << "ID: " << row[0] << ", Name: " << row[1] << ", Age: " << row[2] << std::endl;
        }

        mysql_free_result(res);
    }
};

int main() {
    try {
        MySQLClient client("localhost", "root", "password", "test_db");
        client.leggiRecordMultipli("SELECT * FROM test_table WHERE age > ", 20);
    } catch (const std::exception& e) {
        std::cerr << e.what() << std::endl;
    }
    return 0;
}